Scenes from the game Flappy Bird developed by Nguyen Ha Dong. The game is now getting two-three million downloads per day at the most popular mobile application stores.

"Simple” yet “addictive” and “frustratingly difficult” are common adjectives used to describe the latest game that is now topping both Apple and Google Play stores, Flappy Bird.

Developed by Nguyen Ha Dong – who runs the one-man indie game studio .GEARS in Hanoi – the game is now topping two-three million downloads per day at the most popular online game stores, news website Techcrunch reported.

It first hit the Apple Store in May last year but did not reach the top position until last month. It was introduced on Google Play on January 30 and has since topped the free chart there.

The game now boasts around 18 million users, according to PC Magazine.

It is now pending approval to be launched at the Windows Phone app store and is expected to be available there some time this month.

Dong told The Verge in an interview that the game is racking up around US$50,000 a day from in-app ads.

International game designers and critics have rushed to analyze why Flappy Bird – which is as simple as navigating a pixilated bird through Super Mario-like green pipes by tapping the phone screen to flap the bird’s wings – has become a viral hit.

Most agree that the game’s charms lie in its difficulty, which infuriates most players and inspires them to hit the restart button again and again to get higher scores.

Moreover, its “share” function allows players to complain or brag about their scores on social networks like Facebook and Twitter, tempting others to check it out.

Some analysts have even anticipated that Flappy Bird will beat out Candy Crush to become the game of the year for 2014.

The creator

In an email interview with TechCrunch, Dong, 29, said it took him about three days to complete the programming for Flappy Bird and that he reused artwork from other games.

He said he has been making games for four years, but before Flappy Bird none of his games had “1/100th of that popularity.”

Even though the game has gone viral, it does not have the hallmarks of a paid promotion – a top position achieved through ads or paid downloads, according to TechCrunch.

“It is hard to believe, I understand. I have no resources to do anything else besides upload[ing] the game,” Dong posted on Twitter.

Besides Flappy Bird, Dong’s two other games are also on the Apple Store’s top charts: Super Ball Juggling (currently No. 2) and Shuriken Block (No. 6), an unprecedented achievement for an indie game developer.

It is also an “odd” achievement because there is no cross-promotion built into the games themselves, according to TechCrunch.

The news website said Dong refused to answer questions about his background, saying that he is “not comfortable with being exposed.”

It said he has a Twitter account and has hung around on HTML5gamedevs.com, discussing development, while his .GEARS site is quite basic with no information about the games’ creator.